The present invention relates to novel processes for preparing compounds of the formula I, ##STR2## which are useful intermediates for preparing inhibitors of enkephalinase and angiotensin converting enzyme, including 4S-4.alpha., 7.alpha.(R*), 12b.beta.!!-7-(1-oxo-2(S)-thio-3-phenylpropyl)amino!-1,2,3,4,6,7,8,12b-oc tahydro-6-oxo-pyrido2,1-a !2!benzazepine-4-carboxylic acid and 4S-4.alpha.,7.alpha.(R*), 12b.beta.!!-7-(1-oxo-2(S)-acetylthio-3-phenylpropyl)amino!-1,2,3,4,6,7,8, 12b-octahydro-6-oxo-pyrido2,1-a!2!benzazepine-4-carboxylic acid and pharmaceutically acceptable salts thereof (European Patent Application No. 0 481 522 A1, published 22 Apr. 1992, 209th ACS National Meeting, Division of Medicinal Chemistry, Abst. No. 161 (1995), and European Patent Application No. 657 453 A1, published 14 Jun. 1995) and to novel intermediates thereof.